Bonded Substrate Recess Flatness for Infrared Bonding Verification
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Solution Overview
Problem
In liquid discharge heads, the bonding between substrates is difficult to check for defects using infrared transmission microscopy due to significant height differences in the recessed bottom surface, leading to unclear images and making it hard to detect air bubbles, which can result in ink leakage and reduced discharge performance.
Innovation Solution
A bonded substrate configuration where the second substrate has a recess with a bottom surface height difference of less than 10 μm from the bonding surface, allowing for clear infrared imaging and easy detection of bonding defects, and a communication hole forming part of the fluid restrictor to secure desired channel resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the recess bottom surface has significant height difference, then the channel resistance can be adjusted, but the infrared imaging becomes unclear and bonding defects cannot be detected
Solution Approach 1:
The patent applies local quality by making the recess bottom surface substantially flat in the region where infrared imaging is performed, while allowing height differences in other regions to maintain channel resistance. This selective flatness enables clear bonding defect detection through infrared microscopy without compromising the fluidic function.
2Reliability
If the recess bottom surface is made flat for clear imaging, then bonding defects can be detected, but the channel resistance may not be secured
Solution Approach 1:
The patent implements local quality by differentiating the surface characteristics of the recess: the imaging region is made substantially flat for reliable bonding verification, while other regions maintain appropriate height variations to ensure proper channel resistance and fluid flow characteristics.
3Reliability
If air bubbles are present in the bonding, then ink leakage occurs, but they are hard to detect due to unclear infrared images
Solution Approach 1:
The patent applies local quality by creating a substantially flat recess bottom surface in the imaging region, which enables clear infrared transmission images. This allows air bubbles and bonding defects to be easily detected before assembly, preventing ink leakage and ensuring reliable ink discharge.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates reliable bonding verification and reduces ink leakage, enabling stable and efficient liquid discharge by ensuring proper substrate bonding and channel resistance.
Implementation Method 1
The bonded substrate includes a first substrate and a second substrate bonded to the first substrate. The first substrate includes an individual channel member, a diaphragm member, and a piezoelectric element.
Data Source
AI summary
A bonded substrate includes: a first substrate; and a second substrate having a bonding surface bonded to the first substrate, wherein the second substrate includes a recess having a bottom surface recessed from a surface opposite to the bonding surface, and a difference between the maximum height and the minimum height of the bottom surface from the surface opposite to the bonding surface of the recess is less than 10 μm.